A Method for Creating a Three Dimensional Model from Published Geologic Maps and Cross Sections By Gregory J. Walsh Prepared in cooperation with the Moroccan Ministry of Energy, Mines, Water and the Environment (Ministère de l’Énergie, des Mines, de l’Eau et de l’Environnement - MEM) Google Earth (GE) files: Please note: These files are for visualizing the geology at a regional scale only, and should not be used in any way for site-specific decisionmaking. The original published maps contain more complete geologic information. In Google Earth it is possible to view the geology at much greater scale than that intended by the authors. This gives an impression of greater accuracy than is actually present in the models shown here. [Disclaimer modified from the Google Earth version of Graymer and others (2006).] Open-File Report 2009–1229 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2009 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod. To order this and other USGS information products, visit http://store.usgs.gov. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Walsh, G.J., 2009, A method for creating a three dimensional model from published geologic maps and cross .sections: U.S. Geological Survey Open-File Report 2009–1229, 16 p., available online only at http://pubs.usgs.gov/of/2009/1229/. iii Contact For questions or comments, please send inquiries to: Greg Walsh (E-mail: [email protected]). Downloadable files that are part of this report: This report consists of a text, available in PDF format, and a zip file of KML files (KMZ file). Open the KMZ file in Google Earth and play the tour for a quick flyover of the models. • Google Earth ver. 4.3: File, Open, browse to KMZ file, selectTools, Play Tour. • Google Earth ver. 5.0: File, Open, browse to KMZ file, select Tour in GE 5.0 at the bottom of the Places menu; click the Play Tour icon in the lower right corner of the Places menu. Key software used in this report: Google Earth™ Google SketchUp™ Acknowledgments Gregory Walsh would like to thank Steve Kluge for his applications of the modeling described herein to a map the author completed in western Connecticut. Dave Soller and Rob Stamm provided helpful review comments. Support for recently published work in Morocco came from the Ministère de l’Énergie, des Mines, de l’Eau et de l’Environnement (MEM) under contract through their National Program of Geologic Mapping (PNCG). iv Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Methods...........................................................................................................................................................2 Discussion .....................................................................................................................................................15 References Cited..........................................................................................................................................15 Figures 1. Example of a scanned map of the bedrock geology of the Rochester quadrangle, Vermont ....................................................................................................................3 2. The Edit Image Overlay window showing the Altitude tab ....................................................5 3. The Edit Folder window showing the Description tab ............................................................5 4. The GE window showing the two maps as viewed from a starting location ......................6 5. The Google SketchUp window showing the map (A) and the temporary cube (B) as viewed from in the air to the south-southeast ...................................................7 6. The Google SketchUp window showing A, the vertical plane with the cross section; B, imported onto the plane .........................................................................8 7. To more precisely scale and rotate your cross section .........................................................9 8. Choose your Geographic Location in the Google SketchUp Model Info window .............9 9. The Google SketchUp window showing the map with the cross section properly located ..........................................................................................................................................10 10. Google SketchUp windows showing A, the final appearance of the three cross sections with the map; B, prior to exporting the cross section to Google Earth .............10 11. Google Earth window showing A, the location of the Model in the Places window and the green handles used for resizing the model within its green transparent cube; B, resizing the model; C, moving the model .................................................................12 12. Google Earth window showing the final model with four elements, including two maps and two sets of cross sections ......................................................................................13 13. Cropped Google Earth window showing the Timdghas quadrangle in Morocco ............14 14. Cropped Google Earth window showing the Timdghas quadrangle with the surface map and cross sections, plus the floating map and sections at 8800m altitude ..............14 Introduction 1 A Method for Creating a Three Dimensional Model from Published Geologic Maps and Cross Sections By Gregory J. Walsh Abstract This brief report presents a relatively inexpensive and rapid method for creating a 3D model of geology from published quadrangle-scale maps and cross sections using Google Earth™ and Google SketchUp™ software. An example from the Green Mountains of Vermont, USA, is used to illustrate the step by step methods used to create such a model. A second example is provided from the Jebel Saghro region of the Anti-Atlas Mountains of Morocco. The report was published to help enhance the public’s ability to use and visualize geologic map data. Introduction The virtual globe Google Earth is widely used for visualization of earth science information because it is free and easy to use. Since the release in 2005, Google Earth (GE) has been used by many authors to publish earth science map data, teach geol- ogy by showing the Earth in three dimensions, and create 3D models and virtual field trips (for example, Graymer and others, 2006; Lienkaemper, 2006; De Paor, 2007; De Paor and Sharma, 2007; Kluge, 2007; Kluge and others, 2007; Whitmeyer and others, 2007; Williams and De Paor, 2007; Tewksbury, 2008; McColloch and McColloch, 2008). Recent uses of the Google SketchUp software have led to the development of 3D earth science models that can be directly incorporated into GE scenes (De Paor and others, 2008; McDonald and De Paor, 2008; Whitmeyer and De Paor, 2008; De Paor, 2007). These models create extremely effective visualization tools that can also be used for analysis of temporal changes in 3D models. Given the proper training, both the novice and advanced GE user can quickly create simple 3D models from scanned quadrangle-scale maps and cross sections. A more comprehensive approach in which many aspects of earth science are incorpo- rated into GE is described by De Paor (2007) and De Paor and others (2008). The goal of this report is to describe the steps necessary for rapid creation of a 3D model from published geologic maps and cross sections. Admittedly, the methods in this report do not address the problems associated with accurately viewing the sub- surface, since current versions of GE do not allow subsurface viewing. Despite this shortcoming, the models presented here can accurately portray the geology on the Earth’s surface and the eroded geology aboveground from existing published maps without the need to create complex models. Perhaps in future versions of GE, the viewer will have the ability to toggle off the satellite imagery, or make it semi-transparent as can now be done in GE for water bodies, and see the cross sections below ground with the map still clamped to the surface terrain. This report provides two contrasting examples of the geology in mountainous regions: one in Vermont, U.S.A., a loca- tion that is humid, temperate, and vegetated, and the other in Morocco where it is arid, desert, and unvegetated. The Vermont example shows the bedrock geologic map of the 7.5-minute Rochester, quadrangle (Walsh and Falta, 2001). The area is densely forested and the surface geology is not visible on satellite imagery. The geology consists of complexly deformed Mesopro- terozoic to Early Paleozoic metamorphic rocks with a steeply dipping penetrative foliation. The Morocco example shows the geologic